Cerion (Strophiops) malonei Clench, 1937

Original Description

"Cerion (Strophiops) malonei, new species. Plate 3, fig. 6.

Description. � Shell cylindrical, rather short, smooth to ribbed, solid and widely and deeply umbilicated. Color: fiat white, with no indication of mottling. Whorls: 9 to 10, the last three more or less parallel sided, the remaining whorls narrowing rapidly to form a short slightly convex spire. Spire produced at an angle of 90°-100°. Aperture sub-ovate to sub-quadrate, generally with a fairly straight margin along the parietal wall, the peristome occasionally pinched so that the aperture becomes holostomatous. Columella inclined slightly, supporting a small inconspicuous tooth which is sometimes reduced to a minute, irregular lump. Parietal wall with a large tooth that does not penetrate any distance within the aperture. Lip expanded, thin and not turned backwards. Umbilical perforation wide and very deep-a probe reaching as far back as the nuclear whorls. Suture barely indicated, sometimes the last whorl is offset and smaller than the midwhorl, leaving a small ledge or overhang. Occasionally there is an upturn to the body whorl just before the aperture, so much so that the superior margin of the aperture is close to or even with the whorl above. Sculpture: smooth to somewhat coarsely ribbed, with about 18 to 23 ribs on the body whorl, an unusual character is that the ribs are most strongly developed on the penultimate whorl. Nuclear whorls always smooth. Length 31.5; width 18.6; aperture 9 x 6 mm. (holotype). Length 25.6; width 16.6; aperture 7.6 x 5.7 mm. (average of 7 specimens).

Holotype. � Mus. Comp. Zoöl. No. 112706, 3½ mi. SE. of Simms, Long Id., Bahamas. Russell, McLean, Huntington, Foster, collectors, July, 1936. A large series of paratypes obtained from the same locality.

Remarks. � This species forms a striking parallelism with C. dimidiatum Pfr. of Gibara, Cuba, particularly to the short and squat form known as proteus Pfr. Superficially the resemblance is exceedingly close, but the apertural characters exhibited by C. malonei show a direct relationship to the regina group of the lower Bahama Islands. It would appear rather that C. malonei is an extreme divergent form of this group, connected to the main stock through a more or less intermediate form, C. fernandina herein described. Form parallelisms are very abundant in Cerions, the less pronounced characters, such as the structure of the aperture, columellar and parietal teeth, and particularly the lip seem to be far more stable and indicate relationships in accord with the geographical distribution of the individual elements.

The group of regina, however, is probably directly related to the group of maritimum in which dimidiatum is a species. Most of the species of this latter assemblage are found on the north coast of Cuba." (Clench, 1937:20-21)